Aneurysms occur in blood vessels at sites where, due to age, disease or genetic predisposition of the patient, the strength or resilience of the vessel wall is insufficient to prevent ballooning or stretching of the wall as blood passes through. If the aneurysm is left untreated, the blood vessel wall may expand and rupture, often resulting in death.
To prevent rupturing of an aneurysm, a stent graft may be introduced into a blood vessel percutaneously and deployed to span the aneurysmal sac. Stent grafts include a graft fabric secured to a cylindrical scaffolding or framework of one or more stents. The stent(s) provide rigidity and structure to hold the graft open in a tubular configuration as well as the outward radial force needed to create a seal between the graft and a healthy portion of the vessel wall. Blood flowing through the vessel can be channeled through the hollow interior of the stent graft to reduce, if not eliminate, the stress on the vessel wall at the location of the aneurysmal sac. Stent grafts may reduce the risk of rupture of the blood vessel wall at the aneurysmal site and allow blood to flow through the vessel without interruption.
Aneurysms occurring in the aorta, the largest artery in the human body, may occur in the chest (thoracic aortic aneurysm) or in the abdomen (abdominal aortic aneurysm). Due to the curvature of the aortic arch, thoracic aortic aneurysms can be particularly challenging to treat. Other parts of the vasculature, such as the common iliac artery which extends from the aorta, can also be extremely tortuous. Hence, a stent graft deployed into such regions is preferably able to conform to the vasculature.